The present invention relates to a method and a device for producing heat exchange elements with a tubular base body having a cross-section with a width that is substantially greater than its height and provided with ribs at its outer surface for increasing the heat exchange surface area, and also relates to a respective heat exchange element produced by the method and the device.
In order to increase the heat exchange surface area at heat exchange elements with a tubular base body having a cross-section with a width that is substantially greater than its height, it is known from German Offenlegungsschrift 21 44 465 to slide ribbed sheet metal strips, produced by a stamp, onto the base body in its longitudinal direction because for a tubular base body with a cross-section having a width that is much greater than the respective height a spiral winding of a metal band for producing ribs is not possible. With suitable measures a metal band can be wound onto oval tubes with a width-height-ratio of up to 3; however, for a width-height-ratio greater than 3 it is necessary to use ribbed sheetmetal that is slid onto the base body, even though a greater manufacturing expenditure is needed, because the winding of a metal band would require extremely variable angular radii.
From German Offenlegungsschrift 21 05 070 a method is known for producing heat exchange elements with a tubular base body in which the tubular base body is provided with ribs for increasing the heat exchange surface area, wherein on two oppositely arranged sides of the base body one ribbed sheet metal strip each is applied in the longitudinal direction of the base body, whereby the sheet metal is removed from a roll and is folded (corrugated) by a profiling device before being applied to the base body. It is connected to the surface area of the base body at at least some contact points after pressing the sheet metal against the base body. In this known method the transport of the base body is achieved with two drive rollers driven by a motor. The resulting transporting speed of the base body must be adjusted to the feed speed of the two sheet metal strips. For this purpose, the sheet metal strips are not only driven within the profiling device, that comprises gear wheels and is driven by a motor, but also by further motors within the manufacturing device. The known method requires thus a plurality of drive units which must be exactly adjusted relative to one another in order to be able to produce a flawless product. The expenditure for manufacturing and attaching the ribbed sheet metal strips for increasing the heat exchange surface area is thus considerable.
It is therefore an object of the present invention to provide a heat exchange element as well as a method and device for its manufacture wherein the tubular base body, despite its extreme width-height-ratio can be provided with ribs for increasing the heat exchange surface area by a simple and inexpensive continuous method.